Zynga, which dominates the fast-growing social gaming industry, hopes to raise as much as $2 billion in an initial public stock offering that would be one of the largest this year, according to multiple reports Tuesday.

The IPO, the filing for which could happen as early as Wednesday, would value the San Francisco startup at $15 billion to $20 billion, according to reports in The Wall Street Journal and CNBC. That would make it easily the largest of the new crop of social networking companies that have gone public or filed plans to do so.

Zynga’s IPO will be “by far the hottest of the ones we’ve seen so far,” said Nitsan Hargil, director of research at GreenCrest Capital, a private equity firm.

“This is the first one we’re seeing where the company has very massive revenue,” added Hargil, who said a major investor in Zynga confirmed to him that the company will file its public offering Wednesday.

Representatives for Zynga declined to comment. Founder and CEO Mark Pincus, though, has long said that he has outsize ambitions for Zynga. Last year, he told The New York Times that the opportunity in the social gaming market was “like search before Google came along.”

Creator of ‘FarmVille’

Zynga develops games such as “FarmVille” that users play with friends on Facebook and other social networks. According to the company, about 215 million people play its games monthly.

Zynga makes money largely by charging for virtual goods that can be used in its games. According to a March report in the New York Post, the company expected then to earn $630 million on $1.8 billion in revenue this year.

Backed by some of the top venture capital firms in Silicon Valley, Zynga has raised $219 million in four rounds of financing, according to the company. Among its backers are Digital Sky Technologies, Kleiner Perkins Caufield & Byers, Andreessen Horowitz, LinkedIn founder Reid Hoffman and Clarium Capital President Peter Thiel.

A representative for Andreessen Horowitz declined to comment. Thiel and Kleiner Perkins partner Bing Gordon, who serves on Zynga’s board of directors, did not respond to requests seeking comment.

A growing number of technology startups have debuted on the public markets or filed to go public this year. Social networking site LinkedIn raised some $350 million in a public offering in May. Internet radio company Pandora garnered some $235 million in its IPO this month. And daily deals company Groupon filed for a public offering this month.

Zynga has about 1,300 employees. At a $20 billion valuation, the company would be worth 50 percent more than Activision Blizzard, which is the most valuable public video game company and has about 7,600 employees. Last year, Activision Blizzard earned $418 million on $4.4 billion in sales.

Nimble company

Zynga deserves a higher valuation than traditional game companies such as Activision and Redwood City-based Electronic Arts (ERTS) because it is a more nimble company that is growing faster, Hargil said. While it might take a year or two for EA to launch a new game and another year or two to update it, Zynga can launch a new game in as little as four months and constantly update it, he added, noting that Zynga also has built its business around promoting new games from within its other games.

As a result, Zynga has revenue “that will dwarf EA’s in a couple years,” Hargil said.

According to the reports, Morgan Stanley will be the lead investment bank on Zynga’s offering. A Morgan Stanley representative declined to comment.

Contact Troy Wolverton at 408-840-4285. Follow him at Twitter.com/troywolv.

Troy Wolverton writes the Tech Files column and covers consumer technology as the personal technology columnist for the Bay Area News Group. Previously, he covered Apple and the consumer electronics industry. Earlier, he reported on technology, business and financial issues for TheStreet.com and CNET News.com.